Teas are roughly classified into three types depending on the extent of fermentation in the course of the production thereof, i.e., non fermented teas typified by green tea, semi fermented teas typified by Oolong tea and fully fermented teas typified by black tea, and they have been widely taken all over the world. Since these teas contain a lot of catechins, polyphenol and vitamin C, they are considered to be helpful for diet, beautification, and prevention of lifestyle-related diseases and so on. Thus a large number of investigations with teas have been currently proceeding.
Among all, green tea has been deeply rooted in Japanese culture, and it has been widely utilized not only for drinks but also, for example, for tea powder prepared by powdering teas as drink powder and food materials (see, for example, Patent Document 1). In addition, owing to the recent increasing tendencies toward fitness and nature loving, canned and PET-bottled tea drinks have gained consumers' popularity and have attracted much attention in the field of drinks not only in Japan but also in foreign countries.
In accordance with the diffusion of tea drinks in Japan in recent years, there have been required tasty tea drinks with rich flavor. Generally, expensive first plucked tea is used for producing tea drinks evaluated as being tasty and rich in flavor. Therefore, it is not practical to produce a tea drink with rich flavor by using such first plucked tea due to the high price. Although so-called late plucked teas, i.e., third and fourth plucked teas are less expensive, they have only poor aroma and strong bitterness and astringency. Accordingly, tea drinks produced by using them as the starting materials are inferior in taste, i.e., having strong bitterness and astringency and poor aroma. Therefore, various attempts have been made hitherto to improve the flavor.
For example, Patent Document 2 (JP-A-2003-153651) discloses that various types of teas are blended to impart sweetness in order to relieve bitterness and astringency. However, Patent Document 2 relates to the improvement in the taste, and there is no suggestion or description about aroma. In fact, the tea thus obtained has an improved taste but is unsatisfactory in aroma intensity.
On the other hand, Patent Document 3 (JP-A-2003-144049) discloses a method in which teas are treated with protease and tannase to increase components relating to the taste and the body. However, Patent Document 3 also relates to the improvement in the taste, and there is no suggestion or description about aroma. Moreover, no satisfactory taste can be obtained thereby.
Concerning attempts to improve aroma, there have been proposed methods in which teas employed as the starting materials or tea extracts obtained by extracting teas are treated with hot water with an enzyme such as β-glucosidase to thereby elevate the aroma intensity (see, for example, Patent Document 4). However, these methods are still insufficient in terms of giving a well-balanced and remarkably enriched aroma of various teas, since the tea aroma is seriously out of balance. In the process of tea drinks, moreover, tea aroma is damaged by heating or tea drink aroma is largely impaired by thermal degradation. Therefore, attempts have been made to compensate for the loss by adding synthetic flavors and the like. However, tea drinks having the natural tea aroma, in particular, the freshness of tea have not been obtained yet.
On the other hand, there have been proposed methods of improving the flavor of vegetable juice by treating a starting vegetable with cellulase or the like in the course of the production (see, for example, Patent Document 5). However, no satisfactory result can be obtained thereby. Further, with regard to flowers, it is required that flowers have an intense scent by themselves at the time of appreciation, and oil having a stronger scent is desired in the course of collecting oil from flower.
Patent Document 1JP-A-Hei6-141775Patent Document 2JP-A-2003-153651Patent Document 3JP-A-2003-144049Patent Document 4JP-A-2001-286260Patent Document 5JP-A-2003-135000